U.S. patent application number 14/398467 was filed with the patent office on 2015-04-23 for load cell device.
This patent application is currently assigned to Shekel Scales Co. (2008) Ltd.. The applicant listed for this patent is Shekel Scales Co. (2008) Ltd.. Invention is credited to Michael Trakhimovich.
Application Number | 20150107913 14/398467 |
Document ID | / |
Family ID | 46330663 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150107913 |
Kind Code |
A1 |
Trakhimovich; Michael |
April 23, 2015 |
LOAD CELL DEVICE
Abstract
A weighing scale and a load cell assembly therefor, the weighing
scale including: (a) a weighing platform; (b) a base; and (c) a
load cell arrangement including: (i) a load cell body, disposed
below the platform and above the base, the body secured to the
platform at a first position along a length of the body, and
secured to the base at a second position along the length, the load
cell body having a first cutout window transversely disposed
through the body, the window adapted such that a downward force
exerted on a top face of the weighing platform distorts the window
to form a distorted window; and (ii) at least one strain-sensing
gage, mounted on at least a first surface of the load cell body,
the strain-sensing gage adapted to measure a strain in the first
surface; and (d) an at least a one-dimensional flexure arrangement
having at least a second cutout window transversely disposed
through the body, the second cutout window shaped and positioned to
at least partially absorb an impact delivered to a top surface of
the load cell body.
Inventors: |
Trakhimovich; Michael; (Gan
Ner, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shekel Scales Co. (2008) Ltd. |
Kibbutz Beit-Keshet |
|
IL |
|
|
Assignee: |
Shekel Scales Co. (2008)
Ltd.
Kibbutz Beit-Keshet
IL
|
Family ID: |
46330663 |
Appl. No.: |
14/398467 |
Filed: |
May 2, 2013 |
PCT Filed: |
May 2, 2013 |
PCT NO: |
PCT/IB2013/000821 |
371 Date: |
November 2, 2014 |
Current U.S.
Class: |
177/211 |
Current CPC
Class: |
G01G 3/1412 20130101;
G01G 21/22 20130101; G01G 23/06 20130101; G01G 3/1402 20130101 |
Class at
Publication: |
177/211 |
International
Class: |
G01G 3/14 20060101
G01G003/14; G01G 21/22 20060101 G01G021/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2012 |
GB |
1207656.8 |
Claims
1. A weighing scale comprising: (a) a weighing platform; (b) a
base; and (c) a load cell arrangement including: (i) a load cell
body, disposed below said platform and above said base, said body
secured to said platform at a first position along a length of said
body, and secured to said base at a second position along said
length, said load cell body having a first cutout window
transversely disposed through said body, said window adapted such
that a downward force exerted on a top face of said weighing
platform distorts said window to form a distorted window; and (ii)
at least one strain-sensing gage, mounted on at least a first
surface of said load cell body, said strain-sensing gage adapted to
measure a strain in said first surface; and (d) an at least a
one-dimensional flexure arrangement having at least a second cutout
window transversely disposed through said body, said second cutout
window shaped and positioned to at least partially absorb an impact
delivered to a top surface of said load cell body.
2. The weighing scale of claim 1, said load cell body adapted and
disposed to provide cantilevered support for said weighing
platform.
3-34. (canceled)
35. The weighing scale of claim 2, said first cutout window and
said load cell body adapted such that, when a weight is disposed on
said platform, bending beams in a vicinity of said first cutout
window achieve a substantially double bending position.
36. The weighing scale of claim 35, said second cutout window being
laterally disposed with respect to said first cutout window.
37. The weighing scale of claim 2, said first cutout window and
said flexure arrangement satisfying an equation:
(H.sub.1+H.sub.2)/H.sub.3<0.50, wherein: H.sub.3 is a height of
said first cutout window; H.sub.2 is a height of a protrusion of
said flexure arrangement below a bottom plane of said first cutout
window, H.sub.2 being .gtoreq.0; and H.sub.1 is a height of a
protrusion of said flexure arrangement above a top plane of said
first cutout window, H.sub.1 being .gtoreq.0.
38. The weighing scale of claim 37, wherein
(H.sub.1+H.sub.2)/H.sub.3 is at most 0.20.
39. The weighing scale of claim 1, said first and second positions
being longitudinally disposed at a distance of at least 20% of a
longitudinal length of said load cell body.
40. The weighing scale of claim 1, said second cutout window being
disposed in a proximal side of said load cell body, with respect to
a free end of said load cell body.
41. The weighing scale of claim 1, wherein said second cutout
window is shaped and disposed to at least mitigate a permanent
distortion of said load cell body, when said impact is severe.
42. The weighing scale of claim 1, wherein said second cutout
window includes a plurality of windows, and wherein said second
cutout window is disposed substantially parallel to said top
surface and a bottom surface of said load cell body.
43. The weighing scale of claim 1, further comprising a dampening
arrangement associated with said flexure arrangement.
44. The weighing scale of claim 43, said dampening arrangement
including a vibration suppressing material filling said second
cutout window.
45. The weighing scale of claim 44, said dampening arrangement
adapted and disposed to dampen an amplitude of an electrical signal
associated with said strain in said first surface, with respect to
a strain produced by a load cell arrangement identical to said load
cell arrangement, but being unconnected to said dampening
arrangement.
46. The weighing scale of claim 43, said dampening arrangement
adapted and disposed to dampen an amplitude of an electrical signal
associated with said strain in said first surface, while being
further adapted to reduce a settling time associated with said
impact.
47. The weighing scale of claim 44, said vibration suppressing
material having a Shore A hardness in a range between 35 and
75.
48. The weighing scale of claim 44, said vibration suppressing
material having a modulus of elasticity within a range of 110.sup.6
Pa to 1010.sup.9 Pa.
49. The weighing scale of claim 38, the weighing scale being a
scanner-type weighing scale.
50. The weighing scale of claim 1, said flexure arrangement
disposed, from an impact absorption standpoint, before, and in
series with, said load cell arrangement, with respect to said
impact delivered to said top of said load cell body.
51. The weighing scale of claim 1, said flexure arrangement
disposed, from an impact absorption standpoint, at least partially
in parallel with said load cell arrangement, with respect to said
impact delivered to said top surface of said load cell body.
52. The weighing scale of claim 1, said at least a one-dimensional
flexure arrangement being an at least two-dimensional flexure
arrangement.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application draws priority from UK Patent Application
Serial No. GB1207656.8, filed May 2, 2012, which is hereby
incorporated by reference for all purposes as if fully set forth
herein.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention relates to load cell assemblies and
weighing devices employing such load cell assemblies, and more
particularly, to impact-absorbent load cell assemblies and weighing
devices that are largely impervious to shock forces acting
thereupon.
[0003] Load cells are employed extensively in weighing scales
because of their accuracy in measuring weights. Such load cells, or
transducers, may have a metallic body having a generally
rectangular perimeter. Opposing surfaces of the perimeter may carry
surface-mounted, resistor strain gauges, interconnected to form an
electrical bridge. The central portion of the body may have a
rigidly-designed opening beneath the strain gauges to define a
desired bending curve in the body of the load cell. The body of the
load cell is adapted and disposed to provide cantilevered support
for the weighing platform. Thus, when a weight is applied to the
weighing platform, temporary deformations in the load cell body are
translated into electrical signals that are accurately and
reproducibly responsive to the weight.
[0004] When the weight on the platform is removed, the metallic
load cell body is designed to return to an original, unstressed
condition. However, excessive shock forces applied to the body via
the weighing platform may permanently distort the load cell body,
compromising thereby the accuracy of the bridge-circuit strain
gauges.
SUMMARY OF THE INVENTION
[0005] According to teachings of the present invention there is
provided a weighing scale including: (a) a weighing platform; (b) a
base; and (c) a load cell arrangement including: (i) a load cell
body, disposed below the platform and above the base, the body
secured to the platform at a first position along a length of the
body, and secured to the base at a second position along the
length, the load cell body having a first cutout window
transversely disposed through the body, the window adapted such
that a downward force exerted on a top face of the weighing
platform distorts the window to form a distorted window; and (ii)
at least one strain-sensing gage, mounted on at least a first
surface of the load cell body, the strain-sensing gage adapted to
measure a strain in the first surface; and (d) an at least a
one-dimensional flexure arrangement having at least a second cutout
window transversely disposed through the body, the second cutout
window shaped and positioned to at least partially absorb an impact
delivered to a top surface of the load cell body.
[0006] According to further teachings of the present invention
there is provided a load cell assembly, including: (a) a load cell
arrangement including: (i) a load cell body having a first cutout
window transversely disposed through the body, the window adapted
such that a downward force exerted on a top face of the load cell
body distorts the window to form a distorted window; and (ii) at
least one strain-sensing gage, mounted on at least a first surface
of the load cell body, the strain-sensing gage adapted to measure a
strain in the first surface; and (b) an at least a one-dimensional
flexure arrangement having at least a second cutout window
transversely disposed through the body, the second cutout window
shaped and positioned to at least partially absorb an impact
delivered to a top surface of the load cell body.
[0007] According to still further features in the described
preferred embodiments, the load cell body is adapted and disposed
to provide cantilevered support for the weighing platform.
[0008] According to still further features in the described
preferred embodiments, the at least one strain sensing gage is
adapted to measure the strain at a location in the first surface
that is above and/or below the distorted window.
[0009] According to still further features in the described
preferred embodiments, the first cutout window and the load cell
body are adapted such that, when a weight is disposed on the
platform, bending beams in a vicinity of the first cutout window
achieve a substantially double bending position.
[0010] According to still further features in the described
preferred embodiments, the second cutout window is laterally
disposed with respect to the first cutout window.
[0011] According to still further features in the described
preferred embodiments, the first cutout window and the flexure
arrangement are dimensioned to satisfy an equation:
(H.sub.1+H.sub.2)/H.sub.3<0.50,
wherein H.sub.3 is a height of the first cutout window; H.sub.2 is
a height of a protrusion of the flexure arrangement below a bottom
plane of the first cutout window, H.sub.2 being .gtoreq.0; and
H.sub.1 is a height of a protrusion of the flexure arrangement
above a top plane of the first cutout window, H.sub.1 being
.gtoreq.0.
[0012] According to still further features in the described
preferred embodiments, (H.sub.1+H.sub.2)/H.sub.3 is at most 0.40,
at most 0.30, at most 0.25, at most 0.20, at most 0.10, or at most
0.05.
[0013] According to still further features in the described
preferred embodiments, the first and second positions are
longitudinally disposed at a distance of at least 20%, at least
30%, at least 40%, at least 50%, or at least 60% of a longitudinal
length of the load cell body.
[0014] According to still further features in the described
preferred embodiments, the second cutout window is disposed in a
proximal side of the load cell body, with respect to a free end of
the load cell body.
[0015] According to still further features in the described
preferred embodiments, the second cutout window is shaped and
disposed to inhibit, or at least mitigate, a permanent distortion
of the load cell body, when the impact is severe.
[0016] According to still further features in the described
preferred embodiments, the second cutout window includes a
plurality of windows.
[0017] According to still further features in the described
preferred embodiments, the second cutout window is disposed
substantially parallel to the top surface and a bottom surface of
the load cell body.
[0018] According to still further features in the described
preferred embodiments, the weighing scale further includes a
dampening arrangement associated with the flexure arrangement.
[0019] According to still further features in the described
preferred embodiments, the dampening arrangement includes a
vibration suppressing material filling the second cutout
window.
[0020] According to still further features in the described
preferred embodiments, the dampening arrangement is adapted and
disposed to dampen an amplitude of an electrical signal associated
with the strain in the first surface.
[0021] According to still further features in the described
preferred embodiments, the dampening arrangement is adapted and
disposed to dampen an amplitude of an electrical signal associated
with the strain in the first surface, with respect to a strain
produced by a load cell arrangement identical to the load cell
arrangement, but being unconnected to the dampening
arrangement.
[0022] According to still further features in the described
preferred embodiments, the dampening arrangement is adapted and
disposed to dampen an amplitude of an electrical signal associated
with the strain in the first surface, while being further adapted
to reduce a settling time associated with the impact.
[0023] According to still further features in the described
preferred embodiments, the vibration suppressing material has a
Shore A hardness below 85, below 80, below 75, or below 70.
[0024] According to still further features in the described
preferred embodiments, the vibration suppressing material has a
Shore A hardness in a range between 35 and 75, between 40 and 70,
between 45 and 70, between 50 and 70, between 55 and 70, or between
55 and 65.
[0025] According to still further features in the described
preferred embodiments, the vibration suppressing material has a
Shore A hardness of at least 30, at least 35, at least 40, or at
least 45.
[0026] According to still further features in the described
preferred embodiments, the vibration suppressing material has a
modulus of elasticity of at most 1010.sup.9 Pa, at most 710.sup.9
Pa, at most 510.sup.9 Pa, or at most 210.sup.9 Pa.
[0027] According to still further features in the described
preferred embodiments, the modulus of elasticity of the vibration
suppressing material is at least 0.510.sup.6 Pa, at least 110.sup.6
Pa, at least 210.sup.6 Pa, at least 310.sup.6 Pa, at least
510.sup.6 Pa, or at least 810.sup.6 Pa.
[0028] According to still further features in the described
preferred embodiments, the vibration suppressing material has a
modulus of elasticity within a range of 0.510.sup.6 Pa to
1010.sup.9 Pa, 0.7510.sup.6 Pa to 1010.sup.9 Pa, 110.sup.6 Pa to
1010.sup.9 Pa, 310.sup.6 Pa to 1010.sup.9 Pa, 510.sup.6 Pa to
510.sup.9 Pa, or 110.sup.6 Pa to 1010.sup.6 Pa.
[0029] According to still further features in the described
preferred embodiments, the weighing scale is a scanner-type
weighing scale.
[0030] According to still further features in the described
preferred embodiments, the flexure arrangement is disposed, from an
impact absorption standpoint, before, and in series with, the load
cell arrangement, with respect to the impact delivered to the top
of the load cell body.
[0031] According to still further features in the described
preferred embodiments, the flexure arrangement is disposed, from an
impact absorption standpoint, at least partially in parallel with
the load cell arrangement, with respect to the impact delivered to
the top surface of the load cell body.
[0032] According to still further features in the described
preferred embodiments, the at least a one-dimensional flexure
arrangement is a two-dimensional or an at least two-dimensional
flexure arrangement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The invention is herein described, by way of example only,
with reference to the accompanying drawings. With specific
reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of
illustrative discussion of the preferred embodiments of the present
invention only, and are presented in the cause of providing what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention, the description taken with the
drawings making apparent to those skilled in the art how the
several forms of the invention may be embodied in practice.
Throughout the drawings, like-referenced characters are used to
designate like elements.
[0034] In the drawings:
[0035] FIG. 1A is a simplified perspective view of an exemplary
load cell assembly according to one embodiment of the present
invention.
[0036] FIG. 1B is a schematic side view of the load cell assembly
of FIG. 1A, with a partial cross-sectional view at the left end of
the assembly;
[0037] FIG. 1C is a transverse cross-sectional view of the load
cell assembly of FIG. 1a, taken along the A-A plane shown in FIG.
1B;
[0038] FIG. 1D is a transverse cross-sectional view of the load
cell assembly of FIG. 1A, taken along the B-B plane shown in FIG.
1B;
[0039] FIG. 1E is a schematic top view of the load cell assembly of
FIG. 1A;
[0040] FIG. 1F is a conventional schematic diagram of the strain
gage electronics;
[0041] FIG. 2 is a schematic exemplary exploded view of a weighing
module according to an embodiment of the present invention;
[0042] FIG. 3A is a perspective view showing a top and side of a
double ended bending beam having an integral one-dimensional
flexure;
[0043] FIG. 3B is a perspective view showing a bottom and side of
the load cell assembly of FIG. 3A;
[0044] FIG. 3C is a perspective, partial, cut-open view of the load
cell assembly of FIG. 3A, showing the integral one-dimensional
flexure;
[0045] FIG. 4A is a perspective view showing a top and side of a
double ended bending beam having an integral two-dimensional
flexure;
[0046] FIG. 4B is a perspective view showing a bottom and side of
the load cell assembly of FIG. 4A;
[0047] FIG. 4C is a perspective, partial, cut-open view of the load
cell assembly of FIG. 4A, showing the integral two-dimensional
flexure; and
[0048] FIG. 5 is an exemplary static nodal stress plot showing the
deflection of the flexure arrangement and the load cell arrangement
in one embodiment of the load cell assembly of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] The principles and operation of the shock-absorbent load
cell according to the present invention may be better understood
with reference to the drawings and the accompanying
description.
[0050] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting. Referring now to the
drawings, FIG. 1A is a simplified perspective view of a load cell
and flexure assembly 100 (also termed load cell assembly) according
to one embodiment of the present invention. FIG. 1B provides a
schematic side view of the load cell assembly of FIG. 1A, with a
partial cross-sectional view at the left end of the assembly.
Transverse cross-sectional views are provided in FIG. 1C (along the
A-A line) and FIG. 1D (along the B-B line).
[0051] A load cell body 125 may be made from a block of load cell
quality metal or alloy. Referring collectively to FIGS. 1A-1D, at
least one transverse cutout 110 is formed in a side of the load
cell body, to form bending beams above and below the cutout. These
beams are held in fixed parallel relationship by end blocks 112,
114 on both ends of the load cell body. Load cell arrangement 105
may include strain-sensing gages 120 adapted and positioned to
measure the strains caused by a force applied to the top of the
(free side of) load cell body 125. When a vertical load acts on a
free end (i.e., an end unsupported by the base, as shown in FIG. 2)
130 of load cell body 125, the load cell body undergoes a slight
deflection or distortion, which distortion is measurably sensed by
strain gages 120.
[0052] The load cell body may also have a hole, threaded hole, or
receiving element (not shown) for receiving or connecting to a base
or base element of the weighing system. Towards free end 130 of the
load cell body, a top face 102 of the load cell body may have one
or more hole, threaded hole, or receiving element 104 for receiving
or connecting to a platform of the weighing system.
[0053] Load cell and flexure assembly 100 may also have at least
one transverse cutout or "window" 150 formed in the side of the
load cell body, in lateral position with respect to the transverse
cutout(s) associated with the strain gages 120. In FIGS. 1A, 1B,
and 1D are shown three such windows, disposed one on top of the
other. The windows may be of a substantially rectangular profile.
The ends of the windows may have a rounded or hemi-circular
profile, substantially as shown.
[0054] Windows 150 may advantageously provide additional
flexibility to the load cell body, and absorb excessive impact
delivered to the body. Thus, windows 150 may form or partially form
a flexure or shock-absorbing arrangement 175. Thus, flexure or
shock-absorbing arrangement 175 is integral with load cell body 125
(e.g., both are disposed within a monolithic load cell body such as
a monolithic block of alloy, aluminum metal, or aluminum-containing
alloy suitable for use as a load cell body), within load cell and
flexure assembly 100.
[0055] Windows 150 may be disposed in the proximal side of the load
cell body, with respect to the free end 130 of the load cell body.
In other words, windows 150 may be disposed longitudinally
in-between transverse cutout 110 and free end 130.
[0056] In a preferred embodiment, shown in FIG. 1B, at least one of
windows 150 may be filled, e.g., with an elastomer, to provide a
dampening (vibration suppressing) mechanism 160 to load cell body
125. Typically, all of windows 150 may be filled with a vibration
suppressing material. This mechanism is especially important when
an excessive impact is delivered to the body. Silicone and rubber
may be suitable materials for filling the windows.
[0057] The filling material may have a Shore A hardness below 80,
and more typically, below 75, or below 70. The Shore A hardness may
be at least 30, at least 35, at least 40, or at least 45. The Shore
A hardness may be between 35 and 75, between 40 and 70, between 45
and 70, between 50 and 70, between 55 and 70, or between 55 and
65.
[0058] The filling material may have a modulus of elasticity that
is less than half that of aluminum. More typically, the modulus of
elasticity of the elastomer is less than 1010.sup.9 Pa, less than
710.sup.9 Pa, less than 510.sup.9 Pa, or less than 210.sup.9 Pa.
The modulus of elasticity may be at least 0.510.sup.6 Pa, at least
110.sup.6 Pa, at least 210.sup.6 Pa, at least 310.sup.6 Pa, at
least 510.sup.6 Pa, or at least 810.sup.6 Pa. The modulus of
elasticity may be within the range of 0.510.sup.6 Pa to 1010.sup.9
Pa, 0.7510.sup.6 Pa to 1010.sup.9 Pa, 110.sup.6 Pa to 1010.sup.9
Pa, 310.sup.6 Pa to 1010.sup.9 Pa, 510.sup.6 Pa to 510.sup.9 Pa, or
110.sup.6 Pa to 1010.sup.6 Pa.
[0059] The filling material may advantageously contact an entire,
or substantially entire, perimeter of window 150. The filling
material may contain extremely small pockets of air. For example,
the filler or filling material may have a sponge-like distribution
of air pockets.
[0060] In one embodiment, the shock absorber arrangement is adapted
whereby the arrangement maintains or nearly maintains the profile
or "footprint" of the load cell assembly.
[0061] Referring back to FIG. 1B, the height of transverse cutout
110 is defined as H.sub.3. The height of flexure arrangement 175
extending above the top of transverse cutout 110 is defined as
H.sub.1, and the height of flexure arrangement 175 extending below
the bottom of transverse cutout 110 is defined as H.sub.2. The
minimum value of each of H.sub.1 and H.sub.2 is zero (i.e., H.sub.1
and H.sub.2 do not assume negative values).
[0062] The inventor has found that it may be highly advantageous
for the heights H.sub.1, H.sub.2, and H.sub.3 to satisfy the
relationship:
(H.sub.1+H.sub.2)/H.sub.3<0.50.
It may be of further advantage for (H.sub.1+H.sub.2)/H.sub.3 to be
less than 0.40, less than 0.30, less than 0.25, less than 0.20,
less than 0.15, less than 0.10, or less than 0.05. In some cases it
may be of further advantage for (H.sub.1+H.sub.2)/H.sub.3 to be
substantially zero.
[0063] This structural relationship may enable various low-profile
scale modules, and may also enable facile retrofitting of the
inventive load cell arrangement in existing weighing scales and
weighing scale designs.
[0064] The inventive load cell assemblies may be particularly
suitable for scanner-type weighing scales.
[0065] FIG. 1E provides a schematic top view of the load cell
assembly of FIG. 1A, showing two strain sensing gages 120 disposed
on a top surface of the load cell body.
[0066] FIG. 1F provides a conventional schematic diagram of the
strain gage electronics, which may be used in, or with, the load
cell assemblies and weighing modules of the present invention. The
load cell system may further include a processing unit, such as a
central processing unit (CPU). The processing unit may be
configured to receive the load or strain signals (e.g., from 4
strain gages SG1-SG4) from each particular load cell and to produce
a weight indication based on the load signals, as is known to those
of ordinary skill in the art.
[0067] FIG. 2 is a schematic exemplary exploded view of a weighing
module 200 according to an embodiment of the present invention.
Weighing module 200 may include a load cell assembly such as load
cell assembly 100, a weighing platform 260 disposed generally above
load cell assembly 100, and a weighing module base 270 disposed
generally below load cell assembly 100. Load cell assembly 100 may
be secured to base 270 by means of an anchoring assembly 280, which
may include at least one fastener such as screws 282. Base 270 may
be equipped with a leg or more typically, a plurality of legs 272
adapted to make contact with a surface on which rests weighing
module 200.
[0068] Load cell assembly 100 may be secured to weighing platform
260 by means of a securing arrangement 280, which may include at
least one fastener such as screws 262, adapted to securely attach
platform 260 to load cell assembly 100.
[0069] FIG. 3A is a perspective view showing a top and side of a
double ended bending beam assembly 300 having integral,
one-dimensional flexures 375A, 375B disposed near each longitudinal
end 330A, 330B of beam 300. Flexure 375A, by way of example, may be
disposed longitudinally between transverse cutout 310A associated
therewith, and longitudinal end 330A.
[0070] FIG. 3B provides a perspective view showing a bottom and
side of the load cell assembly of FIG. 3A. Referring collectively
to FIGS. 3A and 3B, double ended bending beam assembly 300 may be
secured within a weighing module in a largely analogous manner to
that shown in FIG. 2, and described hereinabove. Double ended
bending beam assembly 300 may be secured to a weighing module base
by means of an anchoring assembly, which may include at least one
fastener such as screws or complementary fasteners adapted to
securely fit in at least one receptacle such as screwholes 384.
Bending beam assembly 300 may be secured to a weighing platform
(similar to weighing platform 260 shown in FIG. 2) by means of a
platform securing arrangement, which may include at least one
fastener or complementary fastener such as screws, adapted to
securely attach the platform to beam assembly 300 by means of at
least one receptacle such as screwholes 364.
[0071] In this embodiment, screwholes 364 are disposed towards the
ends of beam assembly 300, with respect to each respective load
cell, while screwholes 384 are disposed towards the center of beam
assembly 300, with respect to each respective load cell.
[0072] FIG. 3C provides a perspective, partial, cut-open view of
the load cell and flexure assembly of FIG. 3A, showing the integral
one-dimensional flexure.
[0073] In the embodiment provided in FIGS. 3A-3C, beam assembly 300
may be adapted, when secured within a weighing module as described,
such that a vertical impact (e.g., an object that is slammed down
with great force onto the weighing platform) acts upon
one-dimensional flexures 375A, 375B, while load cell arrangements
305 remain largely or substantially completely unaffected. Thus,
flexures 375A, 375B may serve as a vertical shock-protection
mechanism for the relatively delicate load cell arrangements 305.
Flexures 375A, 375B may be designed and adapted to exhibit, at a
maximum load capacity for the load cell, a vertical deflection that
is at most 3 times, at most 2 times, at most 1.5 times, at most 1.0
times, or at most 0.8 times, the vertical deflection exhibited by
the load cell itself (without the flexure), at that maximum
capacity.
[0074] As described above, at least one of windows 150 may be
filled, e.g., with an elastomer, to suppress vibration and reduce
settling time. Typically, all of windows 150 may be filled with a
vibration suppressing material.
[0075] FIG. 4A is a perspective view showing a top and side of a
double ended bending beam having an integral two-dimensional
flexure (the entire arrangement designated as assembly 400). FIG.
4B is a perspective view showing a bottom and side of assembly 400
of FIG. 4A. FIG. 4C is a perspective, partial, cut-open view of
assembly 400 of FIG. 4A, showing the integral two-dimensional
flexure.
[0076] Referring collectively to FIGS. 4A to 4C, the assembly 400
may be constructed, and may be adapted to operate in a
substantially similar fashion to the double ended bending beam
having an integral one-dimensional flexure described in detail
hereinabove.
[0077] However, the second dimension of the integral
two-dimensional flexure, including top-oriented windows 490, is
adapted to serve as a horizontal shock-absorbing mechanism for the
relatively delicate load cell arrangements 405. In the exemplary
embodiment provided in FIGS. 4A to 4C, the second dimension of the
integral two-dimensional flexure is particularly adapted to act on
forces exerted in a direction M, generally perpendicular to the
longitudinal or long dimension of assembly 400.
[0078] FIG. 5 is an exemplary static nodal stress plot showing the
deflection of the flexure arrangement and the load cell arrangement
in one embodiment of the load cell assembly of the present
invention. It will be appreciated by those of skill in the art that
the bending beams advantageously maintain a substantially double
bending position.
[0079] It will be appreciated that certain features of the
invention, which are, for clarity, described in the context of
separate embodiments, may also be provided in combination in a
single embodiment. Conversely, various features of the invention,
which are, for brevity, described in the context of a single
embodiment, may also be provided separately or in any suitable
sub-combination.
[0080] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims.
* * * * *